RBC immunization in patients with SCD transfused with Rh D, C, and E and K matched RBCs from minority donors. (A) One hundred forty-six specific antibodies in 123 chronically and 59 episodically transfused patients. (B) Number of antibodies per patient. (C) Number of Rh antibodies per patient. (D) Number of patients with anti-D, -C, -E, or -e in their serum and whose RBCs type positive or negative for the antigen.